IOWA CITY - President Barack Obama brought the national political arena to the University of Iowa’s Field House on Thursday to sell the just-passed health care law to the American people. Watch the Full Speech In his first speech since signing the landmark legislation Tuesday, Obama touted the short-term and long-term effects of the law to a boisterous capacity crowd of 3,000 people. In his 30-minute address, Obama also addressed critics of the law head on, saying it is not a government takeover of health care, as some have maintained. “They will see that if Americans like their doctor, they will keep their doctor. If you like your plan, you will keep you plan,” Obama said. “No one will be able to take that away from you.” The president challenged Republicans to campaign against the parts of the law that include tax credits for small businesses, prevents insurance companies from denying coverage for pre-existing conditions and provides free preventive care for senior citizens on Medicare. “If they want to have that fight, they can have it,” Obama said. “Because I don’t believe the American people are going to put the insurance industry back in the driver’s seat.” Protesters gathered near the Field House hours before the president’s arrival. A couple of people heckled Obama inside the Field House, although the crowd was strongly, and loudly, in support of the president. American’s favored the passage of the health care bill 49 percent to 40 percent, according to a USA Today/Gallup Poll released Tuesday. Matt Strawn, chairman of the Republican Party of Iowa, held a morning news conference by phone and criticized Obama for the cost of the plan, estimated at $938 billion over 10 years, and referenced a conservative rally held in Iowa City last night. “Iowans know that we can’t afford this health care bill, and that was on display last night where we had ... between 300 and 400 people in Iowa City, which is the bluest-city in the state” in Iowa, he said. Still, in coming to Iowa City, the White House chose what is mostly friendly territory and returned to a site that helped boost Obama’s presidential bid in the presidential caucuses two years ago. “This is the state that inspired us to keep going, even when the path was uncertain,” Obama said. “We were out of the polls. And because of you, this is the place where change began.” It was three years ago as a presidential hopeful — one trailing in the polls — when Obama came to the UI campus and unveiled his health plan. The new law of course is not entirely the same as what Obama initially proposed. As a candidate, he opposed requiring adults to have health insurance, but the new law has a mandate. Obama also wanted a public plan, a controversial measure that was eventually dropped from the legislation. But Obama touted what the law will do. This year, small businesses will qualify for tax credits to help cover their employees’ health insurance, insurance companies will no longer be able to drop people because they get sick and students can stay on their parent’s insurance until they are 26 years old, Obama said. Within a few years, health insurance exchanges will be created where uninsured people and small businesses can purchase affordable, quality insurance, he said. Overall, it will take four years to implement the plan, he said, so health care costs will not come down overnight. But in the years to come, health care inflation will slow, he said. “We’ll start reducing the waste in the system, from unnecessary tests to unwarranted insurance subsidies,” Obama said. “So that over that time, Americans will save money.” WATCH: Full Speech BUZZ: Use #ICObama or #ObamainIC to contribute via Twitter WATCH: Air Force One lands at the Eastern Iowa Airport WATCH: Raw video of protesters in Iowa City